Amane Gobena glanced over her shoulder several times as she approached the final stretch of Sunday's L.A. Marathon.
Gobena, of Ethiopia, wanted to make sure that no one could threaten her shot at a $75,000 payday.
She had no need to worry.
Gobena won the women's race in 2 hours 27 minutes 37 seconds to earn $25,000.
Countryman Gebo Burka won the men's race in 2:10:37, but his time was not fast enough to overcome the 17-minute 41-second head start afforded the women as part of the event's $50,000 gender challenge.
Gobena crossed the finish line 41 seconds ahead of Burka to collect the bonus.
"I'm building a house," Gobena said through an interpreter, "and definitely that house will be paid off."
It was the second time in the 29-year history of the L.A. Marathon that Ethiopians swept the men's and women's races. In 2011, Markos Geneti won the men's race, Buzunesh Deba the women's.
Burka earned $25,000 and dedicated his first marathon victory to his recently born son.
Joshua George won the men's wheelchair race in 1:33:11. Susannah Scaroni won the women's race in 1:54:54. Each earned $2,500.
More than 25,000 participants took part in the 29th annual marathon, which followed a course from
Temperatures were in the high 50s when the elite runners started and in the 70s when they finished.
Shortly after the wheelchair athletes left the starting line, 10 elite women followed, with Gobena running among a pack that included four other Ethiopian runners and American Lauren Kleppin.
Gobena, 31, finished second in the 2009 L.A. Marathon. She placed sixth in the Dubai Marathon in January and said this week that she was determined to win not only the L.A. Marathon women's race but also the challenge bonus.
Asked Sunday if the runners worked together to make sure that she or another Ethiopian woman would win the challenge, Gobena said she encouraged other Ethiopians to "come forward."
Gobena led after 13.1 miles in 1:12:43. She and Ethiopian Tigist Tufa pulled away from the pack at about the 18th mile, and Gobena began breaking away from Tufa four miles later en route to her fifth marathon victory, her first since 2011.
"I knew she was slowing down a little bit," Gobena, through the interpreter, said of Tufa.
Tufa finished second in 2:28:04. Kleppin was third in a personal-best 2:28:48.
While the women raced mainly in a tight, near-single-file alignment early on, 17 elite men ran in a much looser pack.
Ethiopian Habtamu Asefa led at the halfway point in 1:05:57.
By 19 miles, Burka, Kenyan Lani Rutto and Ethiopian Dawit Wolde were running together in front. At about the 20-mile mark, Burka and Rutto made it a two-man race.
As they ran the 25th and 26th miles, Burka made several pushes, only to be reeled in by Rutto, who was on his heels.
Burka then began moving slightly to the right or left to keep Rutto off balance and in view.
"I thought he would trick me along the line," Burka said through an interpreter. "I had to take different directions to avoid a trick."
Burka, 26, eventually pulled away.
"I was confident I would make a push and tried my best," Rutto said. "But I could not catch him the last time."
Rutto finished in 2:10:48. Defending champion Erick Mose of Kenya was third in 2:12:56.